As a wireless power supply technique, a technique using the magnetic field resonance mode as disclosed in Patent Document 1 has been proposed in recent years, instead of the ones using electromagnetic induction. In the wireless power supply technology under the magnetic field resonance mode, for example, a resonator having a resonance angle frequency ω1 is provided in the power sending apparatus, and a resonator having a resonance angle frequency ω2 is provided in the power receiving apparatus. As the resonator, a resonance circuit in which a coil and condenser are connected is utilized. By synchronizing these resonance angle frequencies ω1 and ω2 and adjusting the size and alignment of the resonators appropriately, a magnetic field coupling state where energy transfer by the magnetic field resonance mode can be performed is generated between the power sending apparatus and the power receiving apparatus, and power is transferred from the resonator of the power sending apparatus to the resonator of the power receiving apparatus wirelessly. According to such a wireless power supply technique, the usage efficiency of power (energy transfer efficiency) is about several dozen % and the distance between the apparatuses can be relatively large, so the power receiving apparatus can be placed about several dozen centimeters away from the power sending apparatus.
Patent Document 1: Japanese Laid-open Patent Publication No. 2009-501510